Electrically driven magnetic shape memory apparatus and method

ABSTRACT

An actuation apparatus may include a magnetic shape memory (MSM) element configured to contract locally at a portion of the MSM element in response to local exposure to a magnetic field distribution component that is substantially perpendicular to a longitudinal axis of the MSM element. The apparatus may further include a plurality of conductive coils laterally offset from the MSM element. Central axes of each conductive coil of the plurality of conductive coils may be substantially parallel to a longitudinal axis of the MSM element.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to electrically driven magneticshape memory apparatuses and methods.

BACKGROUND

Micropumps may be employed in applications where it is desirable totransmit small volumes (e.g., sub-microliter volumes) of fluid from onelocation to another. For example, micropumps may be used to deliversmall doses of drugs to a subject over a period of time.

Some micropumps operate by generating a magnetic field to actuate apumping mechanism. For example, the magnetic field may producedeformations in a magnetic shape memory (MSM) element. The deformationsmay be used to carry a fluid. Changes in the magnetic field may alter aposition of the deformations thereby moving the fluid through themicropump. Often, a permanent magnet is used to generate the magneticfield. Rotating the permanent magnet may produce the changes to themagnetic field that actuate the pumping mechanism.

Micropumps that use permanent magnets to generate a magnetic field foractuating a pump mechanism may be too large and bulky for someapplications. Further, the permanent magnets may produce stray magneticfields that may negatively affect magnetically sensitive equipment ordevices positioned near the micropump. Additionally, micropumps that usepermanent magnets may provide less control over and less customizabilityof the magnetic field. For example, altering a strength of the magneticfield may be difficult when the magnetic field is generated by apermanent magnet.

SUMMARY

Disclosed is a micropump including an electrically driven MSM systemthat may resolve some of the disadvantages discussed above.

In an embodiment, an actuation apparatus includes a magnetic shapememory (MSM) element configured to contract locally at a portion of theMSM element in response to local exposure to a magnetic fielddistribution component that is substantially perpendicular to alongitudinal axis of the MSM element. The apparatus further includes aplurality of conductive coils laterally offset from the MSM element.Central axes of each conductive coil of the plurality of conductivecoils are substantially parallel to the longitudinal axis of the MSMelement.

In an embodiment, the apparatus further includes a plate in contact witha surface of the MSM element. The plate may have a first opening and asecond opening defined therein. The apparatus may also include at leastone anchor fixing a position of the MSM element relative to the plate,relative to the plurality of conductive coils, or both.

In an embodiment, the apparatus further includes a ferromagnetic corepassing through the plurality of conductive coils along the central axesof each conductive coil of the plurality of conductive coils. Theapparatus may also include one or more pole pieces coupled to theferromagnetic core. The ferromagnetic core may include iron, nickel,cobalt, or a combination thereof. The apparatus may include a yokecoupled to the ferromagnetic core. The yoke may form a loop with the MSMelement and the ferromagnetic core.

In an embodiment, the plurality of conductive coils includes at leastthree coils. Each of the central axes of each conductive coil of thethree conductive coils may be aligned. The three conductive coils may bepositioned at intervals along the MSM element.

In an embodiment, the apparatus further includes a controller coupled tothe plurality of conductive coils. The controller may be configured toselectively reverse a direction of at least one electrical current ofelectrical currents applied through the plurality of conductive coils.

In an embodiment, a method includes applying electrical currents througha plurality of conductive coils to generate a magnetic field. Themagnetic field has a magnetic field distribution component that issubstantially perpendicular to a longitudinal axis of a magnetic shapememory (MSM) element. The method further includes selectively reversinga direction of at least one of the electrical currents to change aposition of the magnetic field distribution component relative to theMSM element.

In an embodiment, the method the MSM element contracts locally and formsa neck at a portion of the MSM element in response to local exposure tothe magnetic field distribution component at the portion. The MSMelement may further uncontract at the portion of the MSM element andcontracts at another portion of the MSM element in response to movementof the magnetic field distribution. A position of the neck may bechanged in response to changing the position of the magnetic fielddistribution component.

In an embodiment, the neck forms a cavity between the MSM element and aplate. The method may further include pumping a substance from a firstopening in the plate to a second opening in the plate via the cavity.

In an embodiment, selectively reversing the direction of the at leastone of the electrical currents comprises successively reversing adirection of the electrical currents through multiple conductive coilsof the plurality of conductive coils.

In an embodiment, the magnetic field has another magnetic fielddistribution component that is substantially parallel to thelongitudinal axis of the MSM element. The MSM element may be stabilizedat a portion of the MSM element in response to local exposure to theother magnetic field distribution component at the portion.

In an embodiment, a micropump apparatus includes a pump assembly. Theapparatus further includes a conductive coil assembly positionedproximate to the pump assembly and including a plurality of conductivecoils. The apparatus also includes a pump controller electricallycoupled to the plurality of conductive coils. The pump controller may beconfigured to apply electrical currents through each of the plurality ofconductive coils. The pump controller may be further configured tosuccessively reverse a direction of electrical currents through at leastone of the plurality of conductive coils.

In an embodiment, the pump controller is further configured to receiveuser input. A rate of successively reversing the direction of theelectrical currents through at least one of the plurality of conductivecoils may be determined based on the user input.

In an embodiment, the pump assembly, the conductive coil assembly, andthe pump controller are implemented on or within an integrated circuitdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an embodiment of an electricallydriven magnetic shape memory (MSM) system;

FIG. 2 illustrates a cross section diagram of an embodiment of anelectrically driven MSM system;

FIGS. 3A-3D illustrate cross section diagrams of an embodiment of anelectrically driven MSM system depicted in a first, second, third, andfourth operating state, respectively;

FIG. 4 illustrates a cross section diagram of an embodiment of anelectrically driven MSM; and

FIG. 5 illustrates a cross section diagram of an embodiment of anelectrically driven MSM system depicted in a particular operating state.

While the disclosure is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. However,it should be understood that the disclosure is not intended to belimited to the particular forms disclosed. Rather, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

Referring to FIG. 1, a block diagram of an embodiment of an electricallydriven magnetic shape memory (MSM) system is depicted and generallydesignated 100. The electrically driven MSM system 100 may include apump assembly 110, a conductive coil assembly 130, and a pump controller140.

The conductive coil assembly 130 may include a plurality of conductivecoils 132-137. Each of the conductive coils 132-137 may be configured togenerate a magnetic field in a first direction in response to receivingan electrical current and to generate a magnetic field in a seconddirection, opposite the first direction, in response to the electricalcurrent being reversed. Further, the conductive coil assembly 130 may bepositioned proximate to the pump assembly 130 such that such the pumpassembly 110 is responsive to a magnetic field distribution generated bythe plurality of conductive coils 132-137. Alterations to the magneticfield distribution generated by the conductive coil assembly 130 mayactuate the pump assembly 110 to cause a fluid to be pumped through thepump assembly 110, as described herein. Although FIG. 1 depicts theconductive coil assembly 130 as including six conductive coils, itshould be understood that the conductive coil assembly 130 may includemore or fewer than six conductive coils.

The conductive coil assembly 130 may be electrically coupled to the pumpcontroller 140 via a plurality of connections 142-147. For example, theplurality of connections 142-147 may electrically couple the pumpcontroller 140 to the plurality of conductive coils 132-137 enabling thepump controller 140 to control a magnetic field direction at each coilof the plurality of conductive coils 132-137 within the conductive coilassembly 130. For example, by applying an electrical current to theconnections 142-147, the pump controller 140 may apply electricalcurrents to the plurality of conductive coils 132-137.

During operation, the pump controller 140 may apply currents to theplurality of conductive coils such that a first set of conductive coils(e.g., including the conductive coil 132) induces a magnetic field in afirst direction and a second set of conductive coils (e.g., includingthe conductive coils 133-137) induces a magnetic field in a seconddirection, opposite the first direction. A resultant magnetic fielddistribution may include a compressed portion that passes through theleft side of the pump assembly. The compressed portion of the magneticfield distribution may cause the pump assembly to receive an amount offluid therein (e.g., at the left side of the pump assembly). The pumpcontroller 140 may successively reverse a direction of electricalcurrents through multiple conductive coils of the conductive coils132-137. For example, the pump controller 140 may reverse a direction ofthe conductive coils 133-136, starting with the conductive coil 133 andreversing a direction of the conductive coils 133-136 in turn, finishingwith the conductive coil 136. By successively reversing a direction ofthe conductive coils 133-136, the pump controller 140 may cause thefluid to be pumped through the pump assembly 110 (e.g., from left toright). Alternatively, the pump controller 140 may successively reversea direction of electrical currents through the coils 133-136, startingwith the conductive coil 136 and reversing a direction of electricalcurrents through the conductive coils 133-136 in turn, finishing withthe conductive coil 133, thereby pumping fluid through the pump assembly110 (e.g., from right to left).

In an embodiment, the electrically driven MSM system 100 may include auser interface 150. The user interface 150 may be configured to receiveinput from a user. The user input may be used to determine a rate forpumping a fluid through the pump assembly 110. For example, the pumpcontroller 140 may determine a rate of successively reversing thedirection of the electrical currents through at least one of theconductive coils 133-136 based on the user input. In an embodiment, theuser interface 150 includes an analog input device such as a variableresistor, a variable capacitor, a variable inductor, another type ofanalog input device, or a combination thereof. In an embodiment, theuser interface 150 includes a digital input device such as digitalbuttons, a digital keypad, a keyboard, a touchscreen, another type ofdigital input device, or a combination thereof.

In an embodiment, the electronically driven MSM system 100 isimplemented as an actuation apparatus. For example, the pump assembly110, the conductive coil assembly 130, and the pump controller 140 maybe incorporated into a micropump apparatus usable to pump fluid. In anembodiment, the micropump apparatus is implemented on or within anintegrated circuit device. For example, the pump assembly 110, theconductive coil assembly 130, and the pump controller 140 may be formedwithin layers of an integrated circuit device.

By using the conductive coil assembly 130 including the plurality ofconductive coils 132-137 to actuate the pump assembly 110, theelectrically driven MSM system 100 may be more compact as compared toMSM systems that do not use conductive coils (e.g., MSM systems that usepermanent magnets to actuate a pump assembly). Thus, the electricallydriven MSM system 100 may applicable in a large number of applicationswhere size is a limiting factor. Further, the electrically driven MSMsystem 100 may enable more control over a magnetic field distributiongenerated by the conductive coil assembly 130 than MSM systems that usepermanent magnets to actuate a pump assembly.

Referring to FIG. 2, a cross section diagram of an embodiment of anelectrically driven MSM system is depicted and generally designated 200.The electrically driven MSM system 200 may include a plate 212, anchors220, 222, an MSM element 218, and a plurality of conductive coils232-236. The plate 212, the anchors 220, 222, and the MSM element 218,may correspond to the pump assembly 110. One or more of the conductivecoils 232-236 may correspond one or more of the conductive coils132-137.

The plate 212 may include a first opening 214 and a second opening 216defined therein. Each of the openings 214, 216 may be configured toreceive fluid which may then be pumped to the other opening, asdescribed herein.

The MSM element 218 may be elongated with a longitudinal axis 224running substantially parallel to the plate 212. As used herein, beingsubstantially parallel means that the longitudinal axis 224 is closer tobeing parallel to the plate 212 than to being perpendicular to the plate212. The MSM element 218 may further be in contact with the plate 212blocking a path from the first opening 214 to the second opening 216.For example, a surface of the plate may be in contact with a surface ofthe MSM element 218 to block the path between the first opening 214 andthe second opening 216. The MSM element 218 may be configured tocontract locally at a portion of the MSM element 218 in response tolocal exposure to a magnetic field distribution component that issubstantially perpendicular (for example, closer to being perpendicularthan to being parallel) to the longitudinal axis 224 of the MSM element218. As the magnetic field distribution is applied to the MSM element218 and altered, the MSM element 218 may pump fluid from one of theopenings 214, 216 to the other opening, as described further withreference to FIGS. 3A-3D. The MSM element may include materials such asnickel, manganese, gallium, another type of material, or a combinationthereof. Further descriptions and embodiments of the MSM element 218 maybe described by U.S. patent application Ser. No. 13/550,386, filed onJul. 16, 2012 and entitled, “Actuation Method and Apparatus, Micropump,and PCR Enhancement Method,” hereby incorporated by reference in itsentirety.

The anchors 220, 222 may be coupled to the MSM element 218 and maystabilize the MSM element 218 during operation of the electricallydriven MSM system 200. For example, the anchors 220, 222 may fix aposition of the MSM element 218 relative to the plate 212, relative tothe conductive coils 232-236, or both. Although FIG. 2 depicts twoanchors, in one or more other embodiments, the electrically driven MSMsystem 200 may include more or fewer than two anchors. In an embodiment,the MSM element 218 includes no anchors and is fit into an apparatus(not shown) and held in place by the plate 212.

The conductive coils 232-236 may be laterally offset from the MSMelement such that central axes of each of the conductive coils 232-236are substantially parallel (e.g., closer to being parallel than to beingperpendicular) to the longitudinal axis 224 of the MSM element 218. Inan embodiment the central axes of each of the conductive coils 232-236are aligned along a central axis 238. The conductive coils 232-236 maybe positioned at regular intervals along the MSM element 218. Forexample, the conductive coils 232-236 may be laterally offset from theMSM element 218 and positioned at regular intervals to form a path fromthe first opening 214 to the second opening 216. Although FIG. 2 depictsthe electrically driven MSM system 200 as including five conductivecoils, in one or more other embodiments, the electrically driven MSMsystem 200 may include more or fewer than five conductive coils. In anembodiment, the MSM system 200 includes at least three conductive coils.

The operation of the electrically driven MSM system 200 is describedwith reference to FIGS. 3A-3D. Referring to FIG. 3A, a cross sectiondiagram of an embodiment of an electrically driven MSM system 200 isdepicted in a first operating state. In the first operating state,electrical currents 302-306 may be applied to the conductive coils232-236. For example, a controller (e.g., the controller 140) may applycurrents to connectors (e.g., the connectors 142-147) electricallycoupled to the conductive coils 232-236.

The currents 302-306 through the conductive coils 232-236 may generate amagnetic field distribution as represented by the magnetic field lines310-313. The orientation of particular portions the magnetic fielddistribution, and the corresponding magnetic field lines 310-313, may berepresented by magnetic field arrows 342-349. For example, the current302 may be applied to the conductive coil 232 such that the current 302flows through the conductive coil 232 in a first direction (passingthrough the coil 232 from right to the left). The current 302 maygenerate a portion of the magnetic field distribution that is orientatedfrom left to right as depicted by the magnetic field arrow 342.Likewise, the currents 303-306 may be applied to the conductive coils233-236 such that the currents 303-306 flow through the conductive coils233-236 in a second direction that is opposite the first direction(passing through each of the coils 233-236 from left to right). Thecurrents 303-306 may generate a portion of the magnetic fielddistribution that is orientated from right to left as depicted by themagnetic field arrows 343-346. Hence, in the first operating state, theconductive coil 232 may be used to generate a first portion of themagnetic field distribution orientated in a first direction as depictedby the magnetic field arrow 342 and the conductive coils 233-236 may beused to generate a second portion of the magnetic field distributionorientated in a second direction, opposite the first direction, asdepicted by the magnetic field arrows 343-346.

The first and second portions of the magnetic field may converge betweenthe conductive coil 232 and the conductive coil 233 resulting in acompressed portion of the magnetic field distribution. A component ofthe compressed portion of the magnetic field distribution may beorientated as depicted by the magnetic field arrow 347. For example, thecomponent of the compressed portion of the magnetic field distributionmay be substantially perpendicular (for example, closer to beingperpendicular than to being parallel) to the central axis 238 of theconductive coils 232-236 and to the longitudinal axis 224 of the MSMelement 218.

The MSM element 218 may contract locally at a portion of the MSM element218 that is exposed to the substantially perpendicular component of thecompressed portion of the magnetic field distribution. For example, theMSM element 218 may contract locally and form a neck at of thecompressed portion of the magnetic field. In an embodiment, the MSMelement 218 may compress in one dimension without compressing in theother two dimensions. To illustrate, the MSM element 218 may compress ina first dimension (for example, with reference to FIG. 3A, the firstdimension running from the top of the page to the bottom of the page)without compressing in the other two dimensions (for example, the seconddimension running from the left of the page to the right of the page andthe third dimension running into the page and out of the page).

The neck may result in the formation of a cavity 320 between the plate212 and the MSM element 218. While the electrically driven MSM system200 is in the first state, fluid may be received in the cavity 320 fromthe first opening 214.

As shown in FIG. 3A, other component of the magnetic field distributionmay be orientated as depicted by the magnetic field arrows 348, 349. Forexample, the other components of the magnetic field distribution may besubstantially parallel (for example, closer to being parallel thanperpendicular) to the longitudinal axis 224 of the MSM element 218. TheMSM element 218 may be stabilized (inhibited from contracting) at aportion of the MSM element 218 in response to local exposure to theother magnetic field distribution components at the portion.

Referring to FIG. 3B, a cross section diagram of an embodiment of anelectrically driven MSM system 200 is depicted in a second operatingstate. The electrically driven MSM system 200 may enter the secondoperating state by reversing a direction of the current 303 through thecoil 233. For example, the current 303 may be applied such that thecurrent 303 flows from right to left through the coil 233 instead offrom left to right as in FIG. 3A, thereby inducing a magnetic field thatpasses from left to right as depicted by the magnetic field arrow 343.

In the second operating state, the conductive coils 232 and 233 may beused to generate a first portion of the magnetic field distributionorientated in a first direction as depicted by the magnetic field arrows342, 343, and the conductive coils 234-236 may be used to generate asecond portion of the magnetic field distribution orientated in a seconddirection, opposite the first direction, as depicted by the magneticfield arrows 344-346.

The first and second portions of the magnetic field may converge betweenthe conductive coil 233 and the conductive coil 234 resulting inmovement of the compressed portion of the magnetic field distributionand resulting in movement of the substantially perpendicular component(represented by the magnetic field arrow 347) of the magnetic fielddistribution as compared to FIG. 3A.

The movement of the substantially perpendicular component of themagnetic field distribution component may result in the movement of theneck. For example, the MSM element 218 may compress locally between thecoil 233 and the coil 234 due to the local presence of the substantiallyperpendicular component of the magnetic field distribution anduncompress between the coil 232 and the coil 233 in the local absence ofthe substantially perpendicular component of the magnetic fielddistribution.

The movement of the neck may result in the further movement of thecavity 320. As the cavity 320 moves, following the substantiallyperpendicular portion of the magnetic field distribution, fluid receivedby the cavity during the first operational stage may be moved within thecavity 320 during the second operational stage. Hence, by reversing theelectrical current 303 through the conductive coil 233, fluid may bemoved (pumped) from a first location of the cavity 320 as depicted inFIG. 3A to a second location of the cavity 320 as depicted in FIG. 3B.

Referring to FIG. 3C, a cross section diagram of an embodiment of anelectrically driven MSM system 200 is depicted in a third operatingstate. The electrically driven MSM system 200 may enter the thirdoperating state by reversing a direction of the current 304 through thecoil 234.

In the third operating state, the conductive coils 232-234 may be usedto generate a first portion of the magnetic field distributionorientated in a first direction as depicted by the magnetic field arrows342-344, and the conductive coils 235, 236 may be used to generate asecond portion of the magnetic field distribution orientated in a seconddirection, opposite the first direction, as depicted by the magneticfield arrows 345, 346.

The first and second portions of the magnetic field may converge betweenthe conductive coil 234 and the conductive coil 235 resulting inmovement of the compressed portion of the magnetic field distributionand resulting in movement of the substantially perpendicular component(represented by the magnetic field arrow 347) of the magnetic fielddistribution as compared to FIG. 3B.

The movement of the substantially perpendicular component of themagnetic field distribution component may result in the movement of thecavity 320. By reversing the electrical current 304 through theconductive coil 234, fluid within the cavity 320 may be moved (pumped)from the second location of the cavity 320 as depicted in FIG. 3B to athird location of the cavity 320 as depicted in FIG. 3C.

Referring to FIG. 3D, a cross section diagram of an embodiment of anelectrically driven MSM system 200 is depicted in a fourth operatingstate. The electrically driven MSM system 200 may enter the fourthoperating state by reversing a direction of the current 305 through thecoil 235. By reversing the electrical current 305 through the conductivecoil 235, fluid within the cavity 320 may be moved (pumped) from thethird location of the cavity 320 as depicted in FIG. 3C to a fourthlocation of the cavity 320 as depicted in FIG. 3D.

While the electrically driven MSM system 200 is in the fourth state,fluid may be transmitted from the cavity 320 to the second opening 216.Hence, by progressively reversing multiple conductive coils (e.g., theconductive coils 233-235) fluid may have been pumped through theelectrically driven MSM system 200 from the first opening 214 to thesecond opening 216. Although FIGS. 3A-3D depict the electrically drivenMSM system 200 as pumping fluid from left to right, is should beunderstood that fluid may also be pumped through the electrically drivenMSM system 200 from right to left by progressively reversing anelectrical current through each of the coils 233-235, in starting withthe coil 235.

Although the electrically driven MSM system 200 is depicted in FIGS.3A-3D as including five conductive coils and including four operatingstates, in one or more other embodiments, the electrically driven MSMsystem 200 may include more or fewer than five conductive coils and mayinclude more or fewer than four operating states. For example, in anembodiment, the electrically driven MSM system 200 includes at leastthree conductive coils and at least two operating states. In a firstoperating state, the cavity 320 may be adjacent to the first opening214. In a second operating state, the cavity 320 may be adjacent to thesecond opening 216. In this embodiment, the electrically driven MSMsystem 200 may operate by reversing a direction of at least one of theconductive coils (e.g., between two other conductive coils) to switchbetween the first operating state and the second operating state,thereby moving the cavity from a first position adjacent to the firstopening 214 to a second position adjacent to the second opening 216.

Referring to FIG. 4, a cross section diagram of an embodiment of anelectrically driven MSM system 400 is depicted and generally designated400. The electrically driven MSM system 400 may include the plate 212,the MSM element 218, the anchors 220, 222, and the conductive coils232-236. The electrically driven MSM system 400 may further include aferromagnetic core 410 and a conductive yoke 420. The electricallydriven MSM system may also include pole pieces 431-434 between the coilsand attached to the ferromagnetic core 410 pointing towards the MSMelement 218. For example, the pole piece 431 may be positioned betweenthe conductive coils 232, 233, the pole piece 432 may be positionedbetween the conductive coils 233, 234, the pole piece 433 may bepositioned between conductive coils 234, 235, and pole piece 434 may bepositioned between the conductive coils 235, 236.

The ferromagnetic core 410 may pass through the plurality of conductivecoils 232-236 along a central axis of each conductive coil of theplurality of conductive coils 232-236. For example, the ferromagneticcore 410 may lie along the central axis 238, thereby increasing anintensity of a magnetic field distribution generated by the conductivecoils 232-236. The stronger magnetic field distribution may result agreater compression of the MSM element 218 and a larger cavity forpumping during operation. The larger cavity may enable the electricallydriven MSM system 400 to pump more fluid as compared to systems that donot include a ferromagnetic core. The ferromagnetic core may also enableoperating the pump with smaller current than necessary for operating thepump without ferromagnetic core. The ferromagnetic core may include aferromagnetic material such as iron, nickel, cobalt, anotherferromagnetic material, or a combination thereof.

The yoke 420 may be coupled to the magnetic core 410 and to the anchors220, 222 to form a closed loop between the MSM element 218 and theferromagnetic core 410. Similar to the ferromagnetic core 410, the yoke420 may include a ferromagnetic material such as iron, nickel, cobalt,another ferromagnetic material, or a combination thereof.

Although FIG. 4 depicts the yoke 420 as coupled to the anchors 220, 224,in one or more other embodiments, the magnetic yoke 420 may be incontact with the MSM element 218. For example, other embodiments may notinclude the anchors 220, 222 and the MSM element 218 may be supported bythe yoke 420. Further, although FIG. 4 depicts the ferromagnetic core410 and the yoke 420 as being distinct, in other embodiments, theferromagnetic core 410 and the yoke 420 may be combined. The yoke 420can be made of the same or a different material than the ferromagneticcore 410. In an embodiment, the material is iron-3% silicon. The effectof the ferromagnetic core 410 and the yoke 420 may be enhanced by thepole pieces.

Referring to FIG. 5, a cross section diagram of an embodiment of anelectrically driven MSM system 400 is depicted in a particular operatingstate. Although FIG. 5 depicts only one operating state, it should beunderstood that the electrically driven MSM system 400 may includemultiple operating states such that the cavity 320 may be moved betweenthe first opening 214 and the second opening 216 as described withreference to FIGS. 3A-3D.

In the particular operating state, electrical currents 502-506 may beapplied to the conductive coils 232-236. The electrical currents 502-506may induce an electromagnetic field distribution represented by themagnetic field lines 510, 512. Because the magnetic yoke 420 forms aclosed loop with the MSM element 218 and the magnetic core 410, themagnetic field may be more inhibited from straying from the electricallydriven MSM system 400 as compared to systems that do not include themagnetic yoke such as the electrically driven MSM system 200.

The pole pieces 431-434 may direct the magnetic field lines into the MSMelement. For example in the particular operating state, pole piece 432directs the compressed portion of the magnetic field between theconductive coils 233 and 234 into the MSM element 218.

By directionally limiting the magnetic field distribution, theelectrically driven MSM system 500 may be implemented near magneticallysensitive equipment or devices with limited interference from theelectrically driven MSM system 500 to the magnetically sensitiveequipment or devices.

One or more methods or operations described herein may be performed orinitiated by a processor. For example, a computer readable medium maystore instructions that, when executed by the processor, cause theprocessor to initiate or perform one or more operations. The operationsmay include applying electrical currents through a plurality ofconductive coils to generate a magnetic field. The magnetic field mayhave a magnetic field distribution component that is substantiallyperpendicular to a longitudinal axis of an MSM element, as describedherein. The operations may further include selectively reversing adirection of at least one of the electrical currents to change aposition of the magnetic field distribution component relative to theMSM element, as described herein. The processor may include any type ofprocessing device such as a central processing unit (CPU), a digitalsignal processor (DSP), a peripheral interface controller (PIC), and/oranother type of processing element. The computer readable medium mayinclude any type of non-transitory computer readable medium such as amemory element. For example, the computer readable medium may includerandom access memory (RAM), dynamic RAM (DRAM), read-only memory (ROM),solid state memory, magnetoresistive memory, magnetic disk memory, acompact disc (CD), a digital video disc (DVD), a blu-ray disc, and/oranother type of memory element.

Although various embodiments have been shown and described, the presentdisclosure is not so limited and will be understood to include all suchmodifications and variations are would be apparent to one skilled in theart.

What is claimed is:
 1. A micropump apparatus comprising: a plate havinga surface with a first opening and a second opening defined therein, thefirst opening and the second opening passing through the plate; amagnetic shape memory (MSM) element positioned flush with the surfaceand adjacent to the first opening and the second opening, the MSMelement configured to contract locally and form a neck that defines acavity at a portion of the MSM element in response to local exposure, atthe portion of the MSM element, to a magnetic field distributioncomponent that is substantially perpendicular to a longitudinal axis ofthe MSM element; and a plurality of conductive coils having a commoncentral axis that is laterally offset from the MSM element, the commoncentral axis substantially parallel to the longitudinal axis of the MSMelement, and the plurality of conductive coils spaced along the MSMelement from the first opening of the surface to the second opening ofthe surface.
 2. The apparatus of claim 1, wherein the plate is incontact with a surface of the MSM element.
 3. The apparatus of claim 2,further comprising at least one anchor fixing a position of the MSMelement relative to the plate, relative to the plurality of conductivecoils, or both.
 4. The apparatus of claim 1, further comprising aferromagnetic core passing through the plurality of conductive coilsalong the common central axis.
 5. The apparatus of claim 4, furthercomprising one or more pole pieces coupled to the ferromagnetic core. 6.The apparatus of claim 4, wherein the ferromagnetic core includes iron,nickel, cobalt, or a combination thereof.
 7. The apparatus of claim 4,further comprising a yoke coupled to the ferromagnetic core.
 8. Theapparatus of claim 7, wherein the yoke forms a loop with the MSM elementand the ferromagnetic core.
 9. The apparatus of claim 1, wherein the MSMelement includes nickel, manganese, gallium, or a combination thereof.10. The apparatus of claim 1, wherein the plurality of conductive coilsincludes at least three conductive coils positioned at intervals alongthe MSM element.
 11. The apparatus of claim 1, further comprising acontroller coupled to the plurality of conductive coils, wherein thecontroller is configured to: apply electrical currents to a first set ofthe plurality of coils to induce a magnetic field in a first direction;apply electrical currents to a second set of the plurality of coils toinduce a magnetic field in a second direction opposite the firstdirection; and reverse a direction of at least one of the electricalcurrents.
 12. The apparatus of claim 1, wherein the cavity is definedbetween the portion of the MSM element and the surface.
 13. Theapparatus of claim 12, wherein the MSM element is further configured touncontract at the portion of the MSM element and to contract at anotherportion of the MSM element in response to a movement of the magneticfield distribution component.
 14. The apparatus of claim 12, wherein aposition of the cavity is changed in response to changing a position ofthe magnetic field distribution component.